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Date:   Wed, 25 Mar 2020 21:07:17 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Qian Cai <cai@lca.pw>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        linux-fsdevel@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: Null-ptr-deref due to "sanitized pathwalk machinery (v4)"
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On Wed, Mar 25, 2020 at 03:43:06PM -0400, Qian Cai wrote:

> Since that one has a compilation warning, I have tested this patch and seen no crash so far.
> 
> diff --git a/fs/namei.c b/fs/namei.c
> index 311e33dbac63..73851acdbf3a 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -1806,6 +1806,9 @@ static const char *handle_dots(struct nameidata *nd, int type)
>                                          parent, inode, seq);
>                 }
>  
> +               if (unlikely(error))
> +                       return error;
> +

OK, an equivalent of that had been folded into #work.dotdot/#for-next
I'll definitely throw a mentioning of your reporting that thing;
do you want tested-by: added there as well?